Hermit Crab Water: Fresh Water, Salt Water, and Why Your Crabs Need Both
Hermit crabs need access to both fresh water and marine salt water every day.
They don’t just drink from their pools. Hermit crabs carry water inside their shells and replenish it as needed. This helps keep their abdomen and modified gills moist.
One pool can’t replace the other. Give your crabs both and let them choose.
- Why hermit crabs need both fresh and salt water
- How deep their pools should be
- How to prepare fresh and salt water safely
- How to make pools easy to get in and out of
- How bubblers can improve your water setup
How Deep Should the Water Be?
Deep enough for your largest crab to fully submerge, shell and all.
Depth isn’t the problem when a crab has a safe way out. Add a textured ramp, such as cholla wood, plastic mesh, or rock, that reaches from the bottom of the pool to the rim.
Set up the ramp for your smallest crab, not your largest. It should reach all the way to the bottom so even a tiny crab can climb out.
Can I Use Tap Water?
Yes, but treat it first. Tap water can contain chlorine and chloramines that aren’t safe for hermit crabs.
Prime Water Conditioner treats both. Use treated water for the fresh pool and as the base for your salt water.
How Do You Make Salt Water?
Start with treated fresh water, then add a marine salt mix made for saltwater aquariums. Instant Ocean is one option.
Regular table salt and freshwater aquarium salt don’t have the same mineral balance and should not be used as substitutes.
What About Bubblers?
Bubblers aerate the water and keep it moving.
A small aquarium air pump and air stone are all you need.
Do Hermit Crabs Need Sponges?
No.
Sponges aren’t needed for drinking. Properly prepared fresh and salt water pools give your crabs direct access to the water they need.
Common Water Mistakes
Using untreated tap water. Always treat it with a conditioner that handles both chlorine and chloramines.
Using table salt or freshwater aquarium salt instead of a marine salt mix. They are not substitutes.
Keeping pools too shallow. Both pools should be deep enough for your largest crab to fully submerge, with a safe way in and out.
How Often Should You Change the Water?
It depends on your setup. A small dish that catches substrate and food debris will need changing more often than a larger, filtered pool.
If the water is dirty or something has been dragged into it, change it.
Two pools, always: fresh water and marine salt water.
Treat the water, provide enough depth for full submersion, and make sure your crabs can easily get in and out.